This issue was closed as useless for Firefox in 2010 by the original poster, msg109958.  My participation here is only as tracker triager, as I only have a consumer knowledge of cookies.  Unfortunately, there is no core developer expert for http, let alone the http.cookiejar.  The person who once handled some cookie related patches is no longer active.

Adding a patch to a closed issue is somewhat useless.  In any case, a possible revised PR would be needed.  My suggestion is to ask on python-ideas whether this enhancement might be accepted now and whether better to reopen this issue or open a new one.